1. Field of the Invention
This invention relates to an agent for inhibiting production of hepatitis C virus. In particular, this invention also relates to use of proanthocyanidin.
2. Related Background Art
Hepatitis C virus (hereinafter referred to as HCV) has been found as a major causal virus of non-A non-B hepatic inflammation after blood transfusion. HCV is a single-strand RNA virus having an envelope and belongs to Hepacivirus of Flaviviridae.
In some cases, HCV carriers progress directly to chronic hepatitis without acute hepatitis and then to cirrhosis after many years. About 50 percents of HCV carriers go onto the development of hepatocellular carcinoma. It is said that main cause of such development is persistent infection with HCV. The persistent infection tends to occur even in adults who were infected with HCV after establishing immune system. Even in case of a patient whose site or sites of hepatocellular carcinoma has been completely removed by surgery, the patient still remains at high risk of recurrence, result of the persistent infection repeatedly occurred in unremoved sites.
Japanese Patent Application Laid-Open No. 2007-119398 disclosed that the process materials of blueberry leaves are effective for inhibiting production of HCV. The publication has, however, no disclosure as to any effective chemical substance contained in blueberry leaves.
It is reported in Japanese Patent Application Laid-Open No. 2005-239581 that Pycnogenol or proanthocyanidin has anti-virus activities and is useful to improve the quality of life in carriers of HCV. In this publication, the target virus effective of Pycnogenol is myocarditis virus, but it is not HCV. The inhibition of HCV production, which is unlike myocarditis virus, is not able to evaluate by any model animal except chimpanzee. In view of this, there is no explicit description in the publication about the inhibition of HCV production by proanthocyanidin.
WO2004/047847 refers to an antiviral action of proanthocyanidin and suggests that the proanthocyanidin might be usable for treating hepatic inflammation. Nevertheless, the antiviral action in the publication is against West Nile virus of Flaviviridae. Although HCV belongs to same family, it differs from the West Nile virus in taxonomic genus and the site of infection. The publication has no suggestion as to inhibitory activity of proanthocyanidin for production of HCV.
U.S. Pat. No. 5,211,944 disclosed that a proanthocyanidin polymer composition having 2 to 11 flavonoid units is specifically useful for treating respiratory virus infection such as respiratory syncytial virus, influenza virus and parainfluenza virus infection, but the respiratory virus is quite different from HCV. So, the publication dose not drop any hint about possible activity of proanthocyanidin against HCV production.
These days, the interferon therapy is only effective method for inhibiting production or proliferation of HCV, or eliminating HCV. Even so, around 50 percents of the HCV carriers still remain at risk for onset of hepatocellular carcinoma due to failure to clean HCV completely. It is also suggested that interferon should be administered together with ribavirin to enhance disappearance rate of HCV. Further, continuous dosing of interferon in a low dose has been introduced to inhibit progress of hepatitis C disease and then to retard eventually the onset of hepatocellular carcinoma.
In each case, it is unavoidable to leave some patients who cannot receive the continuous interferon therapy for a long period, because of its strong side-effects such as dehairing, decreased appetite, thrombopenia, depression of white blood cell and so on (See; Shiro Iino, Medical Digest, vol. 46, no. 6, pp. 19-22, 1997).
An object of this invention is to provide an agent for effectively inhibiting production of HCV with fewer side-effects.
Another object of this invention is to provide an agent for inhibiting onset, progress and treating of hepatic disease arisen from HCV.
Further object of this invention is to provide dietary supplements for inhibiting onset or progress of hepatic disease arisen from HCV.